1. Field of the Invention
This invention relates to linear control arrangements, such as fader controls used in audio mixing consoles for mixing a number of audio channels.
2. Description of the Prior Art
It is known for audio mixing consoles to be provided with an audio mix automation facility which allows audio levels to be recorded and replayed referenced to a time code signal synchronized to the audio signals. This facility enables audio balance engineers to build up sound mixes in stages over a period of time. Often, there are so many audio channels that it would otherwise be impractical, even for a number of engineers, to control all the channels successfully in one pass of a mix.
Such systems comprise a number of linear faders, generally one per audio channel, which facilitate control of the audio levels by appropriate movement of the faders. As the faders are moved, referenced to the audio and hence the time code, data from control tracks on the faders is recorded via a computer which is itself referenced to the time code. Subsequently, such as in another pass, the fader movements, which have been recorded as fader data in the computer, may be replayed, again referenced to the audio and the time code. This may, for example, be accomplished by using motorized linear audio faders in the console and arranging for the replay data to control the motorized faders; alternatively the replay data may be supplied to voltage controlled amplifiers or the like for setting the audio level.
In order to instruct the computer to record the fader movement data, switches are normally provided. Also, each fader will generally have at least one switch associated with it in order to enable the individual audio channels to have their fader movement data recorded by the computer. This provision of individual switches for respective faders/channels is necessary to permit mixing in a number of passes. Also, it is necessary if a change to individual channel settings is required subsequently. For example, this may be necessary if a mistaken movement is made during mixing. The error may only apply to a small section of the complete programme. After the error has been identified, the respective part of the programme is replayed and, at the appropriate time, the switch to start recording fader movement data is pressed and the correct fader movements carried out. Since the switch has been pressed, the computer is instructed to overwrite the previous movement data. Once the section to be corrected has finished, the switch is pressed again to stop the computer recording the new movement data and overwriting the previous data. Rather than overwriting the original movement data, this can instead be trimmed so that the original profile is maintained, but at a higher or lower level. By either of these means, an amended section of movement data can be inserted into the previous mix. However, since the switch is normally positioned adjacent the linear fader on the console panel, remixing is generally a two-handed operation, one hand being used to press the switch whilst the other operates the fader knob. Also, extra panel space needs to be provided in order to accommodate the switch; this is a particular disadvantage in a system for mixing a large number of audio channels.